South Australian police say they were alerted around midnight after the child and Ghimire did not return from the beach.
The child was found lost and wandering along The Esplanade at Glenelg North around the same time by a resident.
Police say Ghimire is of Nepali origin while the child is of Indian descent.
A search team has returned this morning to look for the missing man, who police say may have been swimming together with the child.
A search conducted overnight by sea, air and foot failed to locate Ghimire.
Ghimire was wearing a t-shirt, long pants and glasses.
SA Police has asked anyone who saw Ghimire at Glenelg beach or has information on his whereabouts to contact the police assistance line immediately on 131 444.
